A message service, such as an electronic mail service or a social network service (SNS), which is available from a mobile phone or a communication terminal (hereinafter, referred to as a mobile phone), becomes indispensable as a means of communication, and a message system that provides the message service is required to have a high availability without stopping services 24 hours a day and 365 days a year, and a high service quality. The message system that provides the message service is configured to include a plurality of server apparatuses that manages message processing (hereinafter, the server apparatuses will be referred to as servers).
As a method for improving the availability or the service quality of the message system, methods of Patent Literatures 1 and 2 are proposed.
Specifically, there are proposed a method by which a load balancer (or a distribution device) is installed in front of a plurality of servers and the load balancer measures a response time with respect to a request of each server and distributes the loads of the servers (paragraphs 0008 and 0013 of Patent Literature 1), and a method which acquires a load state of each server or a state of garbage collection of Java (registered trademark) VM and distributes messages (paragraphs 0007 and 0028 of Patent Literature 2).
These methods aim to avoid a performance decline of an entire system or a partial service outage even when some servers of the system fall into a failure or a decrease in a processing speed.